Amorphous copolymers of perfluoro-2,2-dimethyl-1,3-dioxole

Abstract

Amorphous copolymer of perfluoro-2,2-dimethyl-1,3-dioxide with at least one fluoro comonomer selected from one or more of ten defined classes having a recited minimum mole proportion of perfluoro-2,2-dimethyl-1,3-dioxole, in no event less than 65%, have high glass transition temperatures of 140 DEG C. or higher, low indices of refraction, and good physical properties, and low dielectric constants, which make them suitable for cladding optical fibers as well as for many electronics applications, including the manufacture of subtrates for circuit boards. They all are soluble at room temperature in perfluoro (2-butyltetrahydrofuran), which makes it practical to apply them as coatings from solution.

I claim: 
     
       1. An amorphous dipolymer of 65-99 mole % of perfluoro-2,2-dimethyl-1,3-dioxole with a complementary amount of tetrafluoroethylene, the glass transition temperature of the copolymer being at least 140° C. 
     
     
       2. A dipolymer of claim 1 which has a glass transition temperature of at least 180° C. 
     
     
       3. A dipolymer of claim 2 which has a glass transition temperature of at least 220° C. 
     
     
       4. A dipolymer of claim 3 wherein the mole proportion of perfluoro-2,2-dimethyl-1,3-dioxole is about 89%, which dipolymer has a glass transition temperature of about 250° C. 
     
     
       5. A dipolymer of claim 1 wherein the mole proportion of tetrafluoroethylene is about 30%, which dipolymer has a glass transition temperatures of about 153° C. 
     
     
       6. A dipolymer of claim 1, wherein the mole proportion of tetrafluoroethylene is about 23%, which dipolymer has a glass transition temperature of about 176° C. 
     
     
       7. A dipolymer of claim 1, wherein the mole proportion of perfluoro-2,2-dimethyl-1,3-dioxole is about 98%.